Fix server error messages

pkg/analysis_server/lib/src/protocol.dart

Index: pkg/analysis_server/lib/src/protocol.dart
diff --git a/pkg/analysis_server/lib/src/protocol.dart b/pkg/analysis_server/lib/src/protocol.dart
index a0854aa871f19f723bc0e74fd904672cd03edf53..8cee0f6d5b0f8160ec5e7a8da587b47cba342e76 100644
--- a/pkg/analysis_server/lib/src/protocol.dart
+++ b/pkg/analysis_server/lib/src/protocol.dart
@@ -594,14 +594,14 @@ class RequestDecoder extends JsonDecoder {
 
   @override
   dynamic mismatch(String jsonPath, String expected) {
-    return new RequestFailure(
-        new Response.invalidParameter(_request, jsonPath, 'be $expected'));
+    return new RequestFailure(new Response.invalidParameter(
+        _request, jsonPath, 'Expected to be $expected'));
   }
 
   @override
   dynamic missingKey(String jsonPath, String key) {
     return new RequestFailure(new Response.invalidParameter(
-        _request, jsonPath, 'contain key ${JSON.encode(key)}'));
+        _request, jsonPath, 'Expected to contain key ${JSON.encode(key)}'));
   }
 }